Electrically conductive revolving joint



v. w. BREITENSTEIN 2,545,939

ELECTRICALLY coNDUcTIvE REvoLvING JOINT March 20, 1951 3 Sheets-Sheet 1f Filed April l, 1947 @ff/77W March 20, 1951 V. W. BREITENSTEINELCTRICALLY CONDUCTIVE REVOLVING JOINT 3 Sheets-Sheet 2 Filed April l,1947 WKZ/677 02.-

W www V. W. BREITENSTEIN ELECTRICALLY CONDUCTIVE REVOLVING JOINT March20, 1951 '3 Sheets-Sheet 5 Filed April l, 1947 Patented Mar. 20, 1951ELECTRICALLY CONDUCTIVE REVOLVING JOINT Victor W. Breitenstein, Chicago,Ill., assignor to Francis N. Bard Application April 1, 1947, Serial No.738,523

6 Claims; 1

This invention relates to a revolving joint, and more particularly to anelectrically conductive joint.

This application is a continuation-in-part of my application Serial No.462,505, filed October 19, 1942, which issued as Patent Number 2,428,-546 on October 7, 1947.

The principalieature of this invention is the use of a single springassembly to urge a plurality of brushes against a contact ring in arevolving joint; another feature of this invention is the provision of apair of springs each of which bear against a plurality of brushes tourge them against the contact ring so that if one spring breaks, theother spring can maintain the urging action; still another feature isthe provision of the springs with one inside the other and each beingwound in a direction opposite to the winding of the other; a stillfurther feature of the invention is the provision of brushes ofsubstantially circular cross-section seated in openings alsosubstantially circular cross-section with the spring or springspreventing rotation of the brushes about their axes. Other features andadvantages of this invention will be apparent from the followingspecication and drawings, in which:

Figure 1 is a vertical sectional view of a revolving joint for aco-axial cable; Figure 2 is a transverse sectional view along the line 22 of Figure 1; Figure 3 is a fragmentary sectional view showing anotherbrush arrangement; Figure 4 is a transverse view along the line 4 4 ofFigure 3, partly broken away; Figure 5 is an'elevational View of anotherform of a fluid and electrically conductive joint; Figure 6 is atransverse View, principally in section, along the line 6 6 of Figure 5;Figure '7 is a longitudinal sectional view along the line 'I 'I ofFigure 7; Figure 8 is a fragmentary sectional detail view along the line8 8 of Figure 6; Figure 9 is an elevation of another embodiment of theinvention; Figure is a fragmentary section lying along line ID--IIJ ofFigure 9; and Figure 11 is a fragmentary section lying along line II-IIof Figure 10.

There are certain applications which require a revolving or swivel jointwhich is both fluid and electrically conductive, and it is to suchjoints that the present application is primarily directed, althoughcertain subcombination features disclosed herein are useful in any typeof electrically conductive revolving joint.

In the particular embodiment of this invention illustrated in Figures1-4, a joint is shown which is particularly designed to enable relativerotational movement between two parts of a coaxial cable, the relativelymovable parts of the joint maintaining uid tight and electricallyconductive contact with each other. In certain types of radio devices itis desirable to revolve the device While providing a high frequencycircuit to it by a co-axial cable, the joint disclosed here beingdesigned for such use at rotational speeds up to about a thousandrevolutions per minute.

Referring now more particularly to Figures 1 and 2, the outer sheath ofthe cable is here shown as comprising separate parts IB and I I, theinner or central conductor being shown as comprising the rod members I2and I3 preferably located within the casing and held in center positionby spacing washers I4, which may be of ceramic or other suitablematerial. The rod member I3 is here shown as having an end portion I5telescopically mounted for movement along the axis of the cable, aspring I6 urging this portion toward the end of the other rod member I2.This end portion I5 has a ball I'I mounted therein the ball providing aconvex portion adapted to be received by a concavity I8 in the end orface of the rod member I2. The concavity has the same radius ofcurvature as the ball I'I, so that the cooperating portions are segmentsof a sphere of the same radius so that a substantial contact area isprovided while limited universal movement between the parts may takeplace. ,While the rod or conductor members I2 and I3 are of copper,theball I'I is preferably of steel and the face having the cooperatingconcavity is prefere ably hardened to secure good wearingcharacteristics. A

Each of the two sheath portionsV Ill-and `II is permanently connected,as by welding, to -one of the two parts I9 and 20 of the joint casing.Each of these parts is generally cylindrical in shape, needle bearings2| facilitating rotation between them. After the part 20 has beenslipped into .the part I9 the cap 22 is screwed in place,.so that theparts aremechanically locked together in a way which enables, relativerotation between them about the axis lof the cable. Suitable .gaskets orpackingmembers, here identified as 23.and24, provide a fluid tight sealduring .suchrelative movement between the parts. This is necessary,since cables of the type here disclosed are generally filled with aninert gas at a pressure of' five or ten pounds to the square inch orthereabouts. Accordingly, there must not only be electrical connectionfrom sheath. to sheathand from central conductor to central'conductorj'b'ut" ring 25, these being here shown as carried by the cap26 and bolted or otherwiseremovably fastened to the casing part i9.openings 2l are drilled in the cap, equally spaced around the cable axisand :parallel .thereto,.:and

A plurality of each of these is adapted to receive a contact unitcomprising a brush 28, a holding member or removed for inspection, thebrushes are.pre

ventedfrom jumping outof the openings in the cap by the. limitingy-meansdescribed above, so .that...a,unit is. provided .whichr may beremoved .and.;easily handled lwithoutloss lor .disassembly of thecontactparts. ThewasherZB should prefE erably bey afairly tight but notabindingt in the .opening 21, so that the whole contactunit can bepulled outand: replacedwhen necessary. By having the brush openings parallel tothe axis of the. cablefairly .long brushes land coil springs can .beused, withgood mechanical characteristics, .Without unduly increasingthe yexternal diameterof the joint. The brushes .may be .of `anyconventional. material, preferably being .carbonmetal, as carboncoppe'r. `Such brushes are hard enough to withstand the `wear .imposedAby rotation at ,speeds approachingathousand revolu- -tions per minute,yet` give reasonably low contact resistance. The joint ,disclosed here,for example, has a contact resistance between its parts less. thanone-fourth. of, any previous similar .joint using brushes vto completethe electrical fcircuit. A` dust .shield 32, of. ber or similarmaterial,prevents carbon. or metal particles from getting into the. cable.

In the modified form of joint shown in Figure 3. and. 4 the brushes3.3.. are mounted for.A radial movement.. and `cooperatewith the outersurface of a'rubbing ring 34. As before, the .rubbingring is .carried byacasing part .rotatablyconnected to thev other casing part 36, thislatter part carrying the brushes,. eachr part .being permanentlyfastened .to one of.,- the sheath .parts .3.1 :and 53.8.

It will be seen that Breviousattempts to Varrange thebrushes radially 4coil spring 39 for urging a plurality of the brushes 33 toward therubbing ring. Instead of a single coil spring co-axial with each brush,this coil spring 39 is arranged in an arc about the center of the cable,with its axis transverse to that of the brushes at its point of contact.The end of the brushes in contact with the spring is preferably notched`slightly to dreceive a portion of the -spring and maintain the 'parts.in .desiredrelationship. With the arrangement shown in Figures 3.; and4 the action of the spring in moving the brushes. in is again limited,this time by engagement-of theV spring'with the surface of the annularportion 40 carrying the brushes. In order `.to insure goodelectricalconnection between the .brushes and the casing individual pigtails 4Iare used.

Another embodiment of this radial arrangementyof .brushes is shown inFigures 5-8 in coinbination with a two passage fluid joint. This formofjoint is not-designed for use with a coaxial cable, but as part of. amachine gunmount in a turret, for example. The details of the fluidjoint, as such, will not be described as they form the subject matter ofthe co-pendingBard et al. application No. 441,074,.1ed. April 30, 1942,now Patent No. 2,343,491. It is sufcient topoint out that this jointprovides two completelyseparate fluid flow pathsbetween its ends-,yetpermit swiveling orrelativerotation between. the parts.

Itis sometimes necessary to carry a vnumber of circuitpaths aswellasaplurality. of fluid flow paths to, thedevice associated withy such ajoint, asa kmachine gun, .and the electrical .arrangement., shown .here,is particularly advantageous for Vsucha purpose. .One of .the joint.parts carries a .plurality of .contact .rings 46a-h, adapted to beconnected .to wiresforming parts ofsaid circuit paths, while.v theother. part 41 carriesV a plurality of. contact arrangements, as maybe,best seenin Figures .6 and 7. .Each of these contact arrangements is,hereshown as comprising three brushes, as 48a, .4817, and. 48C, thesebeingv radially movable .inopenings in an insulating block il!! andhavingtheir inner surfaces in engagementwith the rubbing ring 46h. Asingle coil spring 50 is arranged on an. arc around the axis of thejoint, the ends of the brushes being notched-to atleast partly receiveit, .this single spring yacting to urge all of the brushesintoVoperating contactengagement with thering.. As' before,A thediameterrather than length Lof the coil spring. extends. radially vfrom thejoint,.so that relatively long .brushes may be used -without excessiveincrease in external joint diameter. By making each Aof thecontactassemblies` less thana semi-circle, as may be best seen in Figure 6theycan be arranged on .alternating sides of thejoint-and cooperatewithrubbing rings running. entirely. around the..joint, so thata largenumber of .circuit -paths may be completed within.a small. space. `,Aspringpressed the,contaotgringsclean, and. pig-tails and wires, as 52and 53,V areused to. insuregood-.circuit continuity.

f Inthe. embodimentinFigs.. 9, 10,..and 11,v the brushes 3Q. areofnsubstantially circular .crosssection vand are held in substantiallycircular openings.`r Rotation .of thebrushes about vtheir axes. are..prevented by the springs engaging the notches a in the. outerends ofthe brushes. In .this embodiment ,there are also shown 'a pair ofsprings 5l land 62- insteadv of a singlespring with the spring 82being:of/.smallerdiameter than the spring 6| and the smaller springbeing located within the larger spring. Each spring is wound in adirection opposite to that of the other' spring. With this construction,force is applied to the brushes even though one spring should bieak.

While I have shown and described certain embodiments of my invention, itis to be understood that it is capable of many modications. Changes,therefore, in the construction and arrangement may be made Withoutdeparting from the spirit and scope of the invention as disclosed in theappended claims.

I claim:

1. A revolving electrically conductive joint of the character described,including: a iirst part; a second part, the two parts being mechanicallyconnected for relative rotation about an axis; a metal ring on one ofsaid parts concentric with said axis and in a plane perpendicularthereto; a plurality of brushes each of substantially circularcross-section movably mounted in openings also of substantially circularcross-section in the other part and adapted to make rubbing engagementwith the ring, the movement of said brushes being radial with respect tosaid axis and the outer ends of the brushes being notched; and` a springarranged under tension on an arc about said axis and making engagementwith a plurality of said brushes to urge them toward the ring, thespring being at least partially received in the notches in the outerends of the brushes.

2. A revolving electrically conductive joint of the character described,including: a first part; a second part, the two parts being mechanicallyconnected for relative rotation about an axis; a metal ring on one ofsaid parts concentric with said axis and in a plane perpendicularthereto, said ring being of different material than the part on which itis mounted; a plurality of brushes radially movable in the other partand adapted to make rubbing engagement with the ring; and a springarranged under tension on an arc about said axis and making engagementwith the ends of said brushes remote from said ring to urge the otherends thereagainst.

3. Apparatus of the character claimed in claim 2, wherein there are aplurality of units of such brush and spring assemblies, each beingarranged in an arc of less than a semicircle and all of the springsbeing under tension.

4. A revolving electrically conductive joint of the character described,including: a rst part; a second part, the two parts being mechanicallyconnected for relative rotation about an axis; a metal ring on one ofsaid parts concentric with said axis and in a plane perpendicularthereto; a plurality of brushes movably mounted in4 openings in theother part and adapted to make rubbing engagement with the ring, themovement of said brushes being radial with respect to said axis; and apair of springs arranged under tension on an arc about said axis withboth springs making engagement with the ends of said brushes remote fromsaid ring to urge the other ends thereagainst, one spring being arrangedinside the other and being wound in a direction opposite to the windingof the other.

5. Apparatus of the character described in claim 4, wherein each brushis of substantially circular cross-section and the ends of the brushesare notched to at least partially receive both springs.

6. A revolving electrically conductive joint capable of uniformlytransferring current during rotation at high speeds of revolution,including: a first generally cylindrical casing part, a second generallycylindrical casing part, one of the two parts having a readily removableportion for mechanically connecting the parts for relative rotationabout the axis of the casing and a uid passageway being providedtherethrough; means providing a fluid tight seal between said parts; ametal ring mounted in the second of said parts concentric with said axisand in a plane perpendicular thereto; a plurality of brushes movablymounted in radial openings in said removable portion and adapted to makerubbing engagement with the periphery of said ring; spring means bearingagainst the brushes to urge them toward the ring; means limiting theaction of the spring means, whereby the brushes remain in the openingswhen the parts are separated; two central conductor members lying Yalongsaid axis, each being carried by and movably with one of the casingparts, one of said members having an axially movable end portionadjacent the end portion of the other member, one of said end portionsbeing provided with a concavity and the other with a cooperating convexportion; and spring means for urging said end portions into engagementwith each other.

VICTOR. W. BREITENSTEIN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,512,534 Hadley et al Oct. 21,1924 1,768,565 Campbell July 1, 1930 2,264,998 Miner Dec. 2, 19412,291,070 Bruno July 28, 1942 2,399,823 Phillips May 7, 1946 2,452,144Phillips Oct. 26, 1948 FOREIGN PATENTS Number Country Date 373,036France Mar. 8, 1907

